A vacuum of well-known GOP leaders willing to step up and run for U.S. Senate in Colorado has created one of the largest fields of candidates in state history seeking to oust a sitting Democrat U.S. Senator.

More than a dozen GOP candidates including state senators, county commissioners, veterans and entrepreneurs are vying to topple Sen. Michael Bennet.

During any other election year, it might be a tall order. But in the 2016 presidential election year, toppling one of the state’s top Democrats might not be such a struggle.

Polling numbers demonstrate that Bennet is in deeper trouble than Sen. Mark Udall was at this point during the 2014 midterm election cycle in which Udall was ultimately ousted from his senate seat.

In recent polling, a greater percentage of Colorado voters said they believe Bennet should not be re-elected, than believe he ought to be re-elected.

The current political sentiment certainly hurts the Democrat incumbent this year. Anti-establishment sentiment is running high.

Turnout could hold the key to victory. Thus far, GOP primary election turnout is up 20 percent, while Democrat primary participation is down 15 percent. If that trend continues, Bennet and the Democratic Party could be in for a bruising Colorado loss.

The national political climate could also aid Republicans, even those who don’t have a particularly strong ballot title or political background. It is possible that in a political climate that rewards outsiders during a “change” election, any generic ballot Republican could win over even the most well-known Democratic incumbent.

In Bennet’s case, he is faced not only with the challenge of overcoming his incumbency status but also his baggage of having voted for issues that are not popular with mainstream voters including amnesty for immigrants in the country illegally, banning large-capacity magazines and other gun rights, voting for the Obama administration’s Iran nuclear deal and allegedly flip-flopping on allowing Guantanamo Bay prisoners to be released to Colorado.

Of course, the outcome of the Centennial State’s U.S. Senate race will ultimately come down to the level of Democratic Party voter enthusiasm for presumptive nominee Hillary Clinton, the GOP’s keenness for a candidate such as frontrunner Donald Trump — who has already won 1 million votes this primary season — and good old-fashioned get-out-the-vote efforts on both sides.

The top-polling eight GOP candidates for U.S. Senate are as follows, in alphabetical order:

Robert Blaha (Colorado Springs), a businessman and head of Human Capital Associates, a consulting firm focused on business organization: Blaha suggests he has what it takes to reduce the size of government and solve some of the toughest problems in Washington, D.C. including immigration issues and the ballooning budget deficit.

Charlie Ehler (Fountain), a U.S. Air Force veteran and military industry businessman: Ehler is a liberty-minded candidate who believes in term limits, nationally-legalized marijuana, cracking down on illegal immigration, and balancing the budget.

Jerry Eller (Pueblo West), a U.S. Army veteran and author: Eller is running on a platform of defunding Planned Parenthood, fighting climate change regulations, and reducing the size of government. He served in Operation Desert Storm, Operation Enduring Freedom and Operation Iraqi Freedom.

Ryan Frazier (Aurora), a former city councilman and U.S. Navy veteran: Frazier says his priorities include creating jobs and invigorating the economy, repealing the Affordable Care Act, and reforming education. Raised by a single mother in what he describes a working poor neighborhood, Frazier vowed to give back by founding one of the largest charter schools in Colorado with 800 students.

Darryl Glenn (Colorado Springs), a small-business man and retired U.S. Air Force officer, Glenn is a twice-elected city council member, twice-elected county commissioner and a self-described Christian constitutional conservative. Glenn is running on a platform of preserving the American dream and his priorities are reducing the national debt, fighting Common Core and curbing illegal immigration.

Jack Graham (Fort Collins), a former athletic director at Colorado State University: Graham suggests that Bennet’s support of the Iran nuclear deal was the catalyst to run for office. Graham surprised the political class when he opened his campaign account with a $1 million contribution. Graham is not only a newcomer to campaigning, he is a newcomer to the Republican Party as well, having been registered as a Democrat up until a year ago according to his campaign. But, he has the support of former Colorado GOP chairman Dick Wadhams, who serves as his campaign manager.

Jon Keyser (Jefferson County), a U.S. Air Force veteran of the wars in Iraq and Afghanistan, Bronze Star recipient, a current major in the U.S. Air Force Reserves and a former state representative who resigned his seat to run for U.S. Senate: Keyser is running on a platform of fiscal conservatism. Branded an establishment candidate by himself as well as critics, Keyser boasts voting with both Republicans and Democrats, voting against one of the largest state budgets in Colorado history and receiving a 100 percent rating from the American Conservative Union.

Peg Littleton (El Paso County), an El Paso County commissioner: Littleton has served in government for over a decade, first on the Colorado Board of Education and now as commissioner of Colorado’s most populous county. A former teacher of 15 years, Littleton supports parental rights in education and is a supporter of charter schools. Left-wing critics have called her “Sarah Palin on steroids” — not necessarily a bad ballot title for a Republican primary in which anti-establishment sentiment is running high. But on some issues, Littleton is perhaps not such a hard-line conservative though, having stated she is anti-abortion personally, but does not believe the government should prevent abortions by getting in the way of women who advocate for abortion rights.

Jerry Natividad (Lakewood), a successful business man, a Hispanic and a long-time party activist and donor: Natividad is president of American Facility Services Group and owner of the Jeffco Regional Sports Facility in Lakewood. He has served as a board member of the U.S. Hispanic Chamber of Commerce, the Colorado Chair of the Republican National Hispanic Assembly, and as a member of Mitt Romney’s Hispanic leadership team in 2012. His policy priorities are tackling the national debt, economic growth and the Iran nuclear deal. A self-described moderate, he says both Republicans and Democrats are to blame for a “corrupt” Washington, D.C.

Tim Neville (Littleton), a sitting state Senator: Neville has a track record as a “taxpayer guardian” from the Colorado Union of Taxpayers, has an “A” rating from small government group Principles of Liberty and a 100 percent score and “A” rating from the American Conservative Union. A staunch defender of Second Amendment rights, Neville is backed by the Rocky Mountain Gun Owners Association and the National Association of Gun Rights. Neville also successfully ran a campaign in a swing district and won his seat, a fact he regularly talks about from the campaign trail.

— jennifer@coloradostatesman.com